Eye on Innovation features exciting advances taking place at Mayo Clinic Laboratories. This monthly series shines a spotlight on recently developed tests and highlights how Mayo Clinic translates ideas and discoveries into testing resources that improve diagnosis and care for patients across the globe.

COVID-19 tests typically have relied on nasal swabs or saliva samples. But now, Mayo Clinic Laboratories is offering a new way to test for the virus in tissue specimens.

This first-of-its-kind test detects SARS-CoV-2 (the coronavirus that causes COVID-19) in formalin-fixed, paraffin-embedded tissue. The testing technique is a laboratory-developed modification of the Bio-Rad SARS-CoV-2 droplet digital polymerase chain reaction (ddPCR) test — a method for performing digital PCR based on water-oil emulsion droplet technology — which has received emergency use authorization through the Food and Drug Administration during the COVID-19 pandemic.

Anja Roden, M.D., a medical director in Mayo Clinic's Immunohistochemistry Laboratory who was involved in the development of this test, notes that the tissue test fills a significant gap in COVID-19 detection.

"We did not have an assay to identify SARS-CoV-2 in tissue," she says. "Now this assay can detect the virus not only in lungs, but also in other tissue, which will enhance our knowledge of the virus overall."

The test allows for the identification of SARS-CoV-2 in surgical tissue, which can aid in the detection of COVID-19 in patients who otherwise might have gone undiagnosed, and those diagnoses may lead to better understanding of unusual COVID-19 presentations. The test also can be used after a patient dies to detect the virus in autopsy tissue and confirm a suspected COVID-19 case while increasing understanding of SARS-CoV-2 pathobiology.

This tissue test will serve an important purpose after the worldwide COVID-19 pandemic has passed, as well. "Once the pandemic is over, we likely will not test everyone who has possible symptoms of a COVID-19 infection," Dr. Roden says. "At that point, if we see lung specimens showing morphological findings that could indicate COVID-19, then the test could be useful in positively identifying patients that might be infected."

The COVID-19 tissue test, Severe Acute Respiratory Syndrome Coronavirus 2, RNA Detection, ddPCR, Tissue (Test ID: SCOVT), is now available to order through Mayo Clinic Laboratories.

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